Fused optical fiber optical device system

ABSTRACT

A fused optical fiber optical device system comprises at least one optical component comprising optical fibers and at least one other optical component with which light transmitted in the optical fibers interacts, wherein the optical fiber comprises a core glass of the following composition: La 2 O 3  1–23 mole %, ZrO 2  1–10 mole %, WO 3 ≧2.5 mole %, ZnO 1–15 mole %, BaO 0–9 mole %, B 2 O 3  20–70 mole %, Ta 2 O 5  0–3 mole %, CaO 0–7 mole %, PbO 6–35 mole %, SiO 2  0–40 mole %, As 2 O 3  and/or Sb 2 O 3  0–0.1 mole %, Nb 2 O 5 0–3 mole % and Al 2 O 3  0–8 mole %. The core glass is essentially free of CdO, has a refractive index n d  of at least 1.8 and a CTE of ≧about 74×10 −7 .

Fiber optics deals with the transmission of light through smallfilamentary optical materials or fibers. Typically, the fibers comprisea central core and an outer surrounding cladding along the entire lengthof the fiber. The transmission of light through the fiber is based onthe phenomenon of total internal reflection. For total internalreflection, the refractive index (n) of the core must be greater thanthe refractive index of the cladding. Depending on the application, thematerials used to fabricate the optical fiber vary. A large differenceof refractive index between core glass and cladding glass is generallydesirable.

SUMMARY OF THE INVENTION

The present invention relates to the field of fused optical fiberoptical device systems and more particularly to a device comprising ahigh refractive index optical fiber.

More particularly, the invention relates to a fused optical fiberoptical device system having at least one optical component comprisingoptical fibers and at least one other optical component with which lightfrom said optical fibers interacts.

In a preferred embodiment the optical fibers have a core glass which hasa refractive index of at least 1.8, and a coefficient of thermalexpansion (CTE) of ≧74×10⁻⁷, is essentially free of CdO and has thefollowing composition in mole %:

La₂O₃ 1–23 ZrO₂ 1–10 W0₃ ≧2.5 ZnO 1–15 BaO 0–9  B₂0₃ 20–70  Ta₂O₅ 0–3 CaO 0–7  PbO 6–35 SiO₂ 0–40 As₂0₃ and/or  0–0.1 Sb₂O₃ Nb₂O₅ 0–3 andAl₂0₃ 0–8. 

In another preferred embodiment the core glass of the optical fibers hasa refractive index of at least 1.8, and a CTE of ≧74×10⁻⁷, isessentially free of CdO and PbO and has the following composition inmole %:

La₂O₃ 1–23 ZrO₂ 1–10 W0₃ ≧2.5 Ta₂O₅ 0–3  ZnO 1–15 BaO + CaO ≧4   B₂0₃20–70  Ta₂O₅ 0–3  SiO₂ 0–40 As₂0₃ and/or  0–0.1 Sb₂O₃ Nb₂O₅ 0–3 andAl₂0₃  0–8. 

In yet another preferred embodiment the core glass of the optical fibershas a refractive index of at least 1.8, and a CTE of ≧74×10⁻⁷, isessentially free of CdO, PbO and Ta₂O₅ and has the following compositionin mole %:

La₂O₃ 1–23 ZrO₂ 1–10 W0₃ ≧2.5 ZnO 1–15 BaO + CaO ≧4   B₂0₃ 20–70  SiO₂0–40 As₂0₃ and/or  0–0.1 Sb₂O₃ Nb₂O₅ 0–3 and Al₂0₃  0–8. 

In yet another preferred embodiment the core glass of the optical fibershas a refractive index of at least 1.8, and a CTE of ≧74×10⁻⁷, isessentially free of CdO and Y₂O₃ and has the following composition inmole %:

La₂O₃ 1–23 ZrO₂ 1–10 W0₃ ≧2.85 ZnO 1–15 BaO 0–9  B₂0₃ 20–70  CaO 0–7 PbO 5–35 SiO₂ 0–40 As₂0₃ and/or  0–0.1 Sb₂O₃ Nb₂O₅ 0–3  Al₂0₃ 0–8 andTa₂O₅  0–2.9.

In addition to cadmium free compositions, it is also preferred in thisinvention to provide systems with reduced or absent contents of arsenic,lead, yttrium and tantalum. The glass compositions of use in the coresof the optical fiber systems of the present invention advantageouslysignificantly decrease or eliminate the levels of oxides of lead,yttrium, tantalum, arsenic and/or cadmium found in traditional coreglass compositions without any significant adverse effects on opticaland physical properties.

Good fusibility and meltability of the core glass compositions of use inthe optical fiber systems of the present invention are achieved bybalanced proportions of glass formers (e.g., SiO₂, B₂O₃) in relation tothe poorly melting highly refractive components (e.g., BaO, CaO, WO₃,ZrO₂).

The core glass compositions used in the present invention preferablycontain about 20–70 mole % of the main glass former B₂O₃, particularlypreferably about 25–50 mole %, and most preferably about 30–40 mole %.Another glass former, SiO₂, is present in amounts of about 0–40 mole %.Most preferably, the compositions contain about 9–15 mole % of SiO₂.

Tungsten oxide WO_(3 is) present in an amount of ≧2.5 mole % in theglass and, in addition to the fine adjustment of the optical position,tungsten oxide serves to further reduce the tendency towardscrystallization in a glass system. A WO₃ content of ≧2.5 by mole ispreferred, particularly preferably ≧2.75 mole % and most preferably≧2.85 mole %. Typically the amount of WO₃ is less than 6 mole %.

The core glass compositions of use in the present invention preferablycontain ≦3 mole % of Ta₂O₅, preferably about 0–2 mole %, particularlypreferably about 0–1.5 mole % and for certain embodiments are preferablyTa₂O₅ free. In certain embodiments, the maximum sum of WO₃+Ta₂O₅ takentogether is preferably about 3.5–10 mole %, most preferably about3.5–7.5 mole %.

For stabilization of crystallization and durability, the core glassesmay contain a ZrO₂ content of about 1–10 mole %, preferably about5–10-mole % and most preferably about 6–9 mole %.

For increasing the refractive index and enhancement of dispersioncharacteristics, a BaO content of about 0–9 mole % is preferred,particularly preferably about 0–5 mole % and most preferably about2–4.50 mole %. A La₂O₃ content of about 1–23 mole % is preferred,particularly preferably about 5–15 mole % and most preferably about 7–13mole %.

In general, Sb₂O₃ can be used in place of or in combination with As₂O₃,and is especially useful when As₂O₃ is absent. Sb₂O₃ is typically usedin amounts of 0–0.1 mole %.

Preferably, the alkaline-earth components CaO and BaO taken togethercomprise ≧4 mole %, particularly preferably ≧6 mole %, and mostpreferably ≧8 mole %. Typically the amount of CaO+BaO is less than 16mole %. In certain embodiments niobium oxide can be used advantageouslyto increase refractive index of the glass and improve its durability. ANb₂O₅ content of about 0–3 mole % is preferred, particularly preferablyabout 0–2 mole % and especially 0–1 mole %. According to another aspectof the present invention, the novel core glass compositions of use inthe optical fiber system of the present invention have a CTE of≧74×10⁻⁷, particularly preferably a CTE of ≧75×10⁻⁷ and most preferablya CTE of ≧76×10⁻⁷, e.g., around 76, 77, 78, 79, 80, etc. According toanother aspect, the refractive index (sodium d-line, 589.29 nm) is atleast 1.8, e.g., about any of 1.800, 1.805, 1.801, 1.815, 1.820, 1.825,1.830, 1.835, etc.

All the glass fiber components of this invention can be preparedconventionally. Typically, core glass rods are drawn from molten liquidhaving the desired composition. An alternative is to mold the moltenliquid in special molds. Light transmission optical fibers can bemanufactured by means of the preferred core glass compositions disclosedherein and an appropriate cladding glass in accordance with knownmethods (e.g., a double crucible method or a rod-in-tube method). Abundle of fibers can be made from a plurality of glass fibers. Bytwisting a bundle of fibers, a twister is obtained. This twister rotatesthe image coming from, for example, a photomultiplier and can be usedin, e.g., night-vision telescopes. Methods for cladding core glasses,drawing rods, assembling bundles etc. are all conventional, e.g., see W.B. Allan, Fibre Optics, Theory and Practice, Plenum press 1973; J.Wilbur Hicks, Jr. and Paul Kiritsy, “Fiber Optics”, Glass IndustryApril–May 1962; J. Hecht, Understanding Fiber Optics, Prentice Hall,1999.

The glass composition ranges according to the invention offer a group ofcadmium-free optical core glasses, which have improved properties. Withthese properties, especially with their optical positions, the resultantoptical fibers are outstandingly suitable for use in the opticalapplications of, for example, tapers for X-ray imaging, crystallography,protein crystallography, astronomical imaging arrays, transfer windows,cell phones, sensors e.g., biometric, night vision technology, e.g.,goggles, telescopes, telescope optics, etc., beam splitter technology,e.g., beam splitters, etc., imaging, e.g., transmission tapers,twisters, etc. projection, telecommunication and laser technology, etc.,where, other than as specified herein, they are employed conventionally.

The fused optical fiber optical device systems of this invention includesystems routinely found in such applications, often including one ormore of light sources, lenses, windows, beam splitters, reflective ortransmissive surfaces, optical detectors (CCD's etc.), detector arrays,phosphor coatings, bandpass filters, sensor arrays, filter coatings,multi-channel plates, microprocessors, display elements (LCD, LED,etc.), etc. The optical fiber components of this invention can be usedtogether with such components or as part of such components, etc. Suchconfigurations are conventional [See e.g., T. Gibson, “Seeing in theDark” American Heritage of Invention and Technology, 14(1) pp 47–54(1998); I. P. Csorba, (book) Image Tubes, Sams &Co. (1985)].

Without further elaboration, it is believed that one skilled in the artcan, using the preceding description, utilize the present invention toits fullest extent. The following preferred specific embodiments are,therefore, to be construed as merely illustrative, and not limitative ofthe remainder of the disclosure in any way whatsoever.

In the foregoing and in the following examples, all temperatures are setforth uncorrected in degrees Celsius and, all parts and percentages areby mole %, unless otherwise indicated.

EXAMPLES

Glasses according to the invention are produced from customary rawmaterials by melting. Tables 1–3 show the respective composition (inmole %, based on oxide), the refractive index n_(d), the CTE and theglass transition temperature T_(g) [° C.] of the example glasses.

TABLE 1 1 2 3 4 5 6 La₂O₃ 10.99% 11.14% 11.14% 11.14% 11.14% 11.14% ZrO₂6.13% 6.21% 6.21% 6.21% 6.21% 6.21% WO₃ 2.86% 2.89% 2.89% 2.89% 2.89%2.89% ZnO 12.86% 11.85% 11.85% 11.85% 11.85% 11.85% BaO 5.49% 4.24%4.24% 4.24% 4.24% 4.24% B₂O₃ 36.96% 35.97% 36.43% 36.43% 36.42% 36.43%Ta₂O₅ 2.99% 2.63% 2.33% 2.23% 2.03% 1.72% CaO 4.79% 4.86% 4.86% 4.86%4.86% 4.86% PbO 4.82% 8.08% 8.44% 8.61% 9.07% 9.76% SiO₂ 12.05% 12.07%11.55% 11.48% 11.23% 10.84% As₂O₃ 0.06% 0.06% 0.06% 0.06% 0.06% 0.06%Ref. Index measurement 1.80962 1.8171 1.8193 Ref. Index Becke 1.79 1.7851.785 1.805 1.805 Line at SFO dispersion 39.56 37.88 CTE (×10⁻⁷) 75.776.6 76.7 Tg (° C.) 598 581 577 Soft. Pt. (° C.) 692 680 Strain Pt. (°C.) 542 545 Anneal Pt. (° C.) 572 575 Working Pt. (° C.) Knoop Hard.Density (g/cm³)

TABLE 2 7 8 9 10 11 12 13 La₂O₃ 11.14% 11.14% 11.13% 11.14% 10.99%11.14% 10.99% ZrO₂ 6.21% 6.21% 6.75% 6.21% 6.13% 6.21%  6.25% WO₃ 2.89%2.89% 2.89% 2.89% 2.85% 2.89%  2.85% ZnO 11.85% 11.85% 11.36% 11.86%12.86% 11.85% 12.86% BaO 4.24% 4.24% 4.24% 4.24% 5.49% 4.24%  7.00% B₂O₃36.42% 36.43% 36.42% 36.43% 38.14% 36.43% 37.30% Ta₂O₅ 1.42% 1.11% 0.91%0.91% 2.99% 1.42%    2% CaO 4.86% 4.86% 4.86% 4.86% 4.79% 4.86%  5.49%PbO 10.47% 11.08% 11.45% 11.07% 0.00% 10.13%  0.00% SiO₂ 10.44% 10.13%9.93% 10.33% 13.20% 10.77% 12.70% As₂O₃ 0.06% 0.06% 0.06% 0.06% 0.06%0.06%  0.06% Nb₂O₅ 2.50%  1.20% Ref. Index 1.8182 1.817 1.817 1.818measurement Ref. Index 1.805 1.815 1.808 1.805 Becke Line at SFOdispersion CTE (×10⁻⁷) 77.0 70.94 76.7 73.55 Tg (° C.) 578 575 Soft. Pt.(° C.) 670 Strain Pt. (° C.) 576 Anneal Pt. (° C.) 543 590 Working Pt.573 781 (° C.) Knoop Hard. 600 Density (g/cm³) 4.847

TABLE 3 14 15 La₂O₃ 11.49% 11.49% ZrO₂ 7.00% 7.10% WO₃ 3.50% 3.50% ZnO12.86% 13.16% BaO 6.80% 6.80% B₂O₃ 37.30% 37.50% Ta₂O₅ 0.00% 0.00% CaO5.79% 5.79% PbO 0.00% 0.00% SiO₂ 13.40% 13.40% As₂O₃ 0.06% 0.06% Nb₂O₅1.80% 1.20% Ref. Index 1.808 1.800 measurement CTE (×10⁻⁷) 74.2 74.2

The glasses according to the invention are produced as follows: the rawmaterials for the oxides are weighed out. The refining agent or agentsare added, and thorough mixing is carried out. The glass mixture ismelted at about 1300° C. in a continuous Pt melting unit or 2I crucible,refined at about 1427° C. and thoroughly homogenized. At a pouringtemperature of about 1149° C., the glass is poured and is processed togive the desired dimensions.

The preceding examples can be repeated with similar success bysubstituting the generically or specifically described reactants and/oroperating conditions of this invention for those used in the precedingexamples. From the foregoing description, one skilled in the art caneasily ascertain the essential characteristics of this invention and,without departing from the spirit and scope thereof, can make variouschanges and modifications of the invention to adapt it to various usagesand conditions.

1. A fused optical fiber optical device system comprising at least oneoptical component comprising optical fibers and at least one otheroptical component with which light transmitted in said optical fibersinteracts, wherein said optical fibers comprise a core glass of thefollowing composition in mole %: La₂O₃ 1–23 ZrO₂ 1–10 W0₃ ≧2.5 ZnO 1–15BaO 0–9  B₂0₃ 20–70  Ta₂O₅ 0–3  CaO 0–7  PbO 6–35 SiO₂ 0–40 As₂O₃  0–0.1Sb₂O₃  0–0.1 Nb₂O₅ 0–3  Al₂0₃ 0–8 

and essentially free of CdO with a refractive index n_(d) of at least1.8 and a CTE of ≧74×10⁻⁷.
 2. The optical device system of claim 1,wherein the amount of Ta₂O₅ is 0–2-mole %.
 3. The optical device systemof claim 2, wherein the amount of Ta₂O₅ is 0–1.5-mole %.
 4. The opticaldevice system of claim 1, wherein the amount of WO₃ is ≧2.75 mole %. 5.The optical device system of claim 1, wherein the CTE is ≧75×10⁻⁷. 6.The optical device system of claim 5, wherein the CTE is ≧76×10⁻⁷. 7.The optical device system of claim 1, wherein the amount of PbO is about9–35 mole %.
 8. The optical device system of claim 7, wherein the amountof PbO is about 10–35 mole %.
 9. The optical device system of claim 1which is a night vision telescope.
 10. The optical device system ofclaim 1 which comprises night vision goggles.
 11. The optical devicesystem of claim 1 which comprises a beam splitter.
 12. The opticaldevice system of claim 1, wherein the amount of BaO+CaO is about ≧4 mole%.
 13. The optical device system of claim 12, wherein the amount ofBaO+CaO is about ≧6 mole %.
 14. The optical device system of claim 13,wherein the amount of BaO+CaO is about ≧8 mole %.
 15. The optical devicesystem of claim 13, wherein the amount of WO₃+Ta₂O₅ is about 3.5–7.5mole %.
 16. The optical device system of claim 1, wherein the amount ofSiO₂ is from 9–40 mole %.
 17. The optical device system of claim 1,wherein said core glass has a refractive index n_(d) consistingessentially of at least 1.8.
 18. A fused optical fiber optical devicesystem comprising at least one optical component comprising opticalfibers and at least one other optical component with which lighttransmitted in said optical fibers interacts, wherein said opticalfibers comprise a core glass of the following composition in mole %:La₂O₃ 1–23 ZrO₂ 1–10 W0₃ ≧2.5 Ta₂O₅ 0–3  ZnO 1–15 BaO + CaO ≧4   B₂0₃20–70  Ta₂O₅ 0–3  SiO₂ 0–40 As₂O₃  0–0.1 Sb₂O₃  0–0.1 Nb₂O₅ 0–3  Al₂0₃0–8 

and essentially free of CdO and PbO with a refractive index n_(d) atleast 1.8 and a CTE of ≧74×10⁻⁷.
 19. The optical device system of claim18, wherein the amount of Ta₂O₅ is about 0–2-mole %.
 20. The opticaldevice system of claim 19, wherein the amount of Ta₂O₅ is about0–1.5-mole %.
 21. The optical device system of claim 18, wherein theamount of WO₃ is ≧about 2.75 mole %.
 22. The optical device system ofclaim 18, wherein the CTE is ≧about 75×10⁻⁷.
 23. The optical devicesystem of claim 18, which is a night vision telescope.
 24. The opticaldevice system of claim 18, which comprises night vision goggles.
 25. Theoptical device system of claim 18, wherein the amount of SiO₂ is from9–40 mole %.
 26. The optical device system of claim 18, wherein theamount of B₂O₃ is from 25–70 mole %.
 27. A fused optical fiber opticaldevice system comprising at least one optical component comprisingoptical fibers and at least one other optical component with which lighttransmitted in said optical fibers interacts, wherein said opticalfibers comprise a core glass of the following composition in mole %:La₂O₃ 1–23 ZrO₂ 1–10 W0₃ ≧2.5 ZnO 1–15 BaO + CaO ≧4   B₂0₃ 20–70  SiO₂0–40 As₂O₃  0–0.1 Sb₂O₃  0–0.1 Nb₂O₅ 0–3  Al₂0₃ 0–8 

and essentially free of CdO, PbO and Ta₂O₅ with a refractive index n_(d)at least 1.8 and a CTE of ≧74×10⁻⁷.
 28. The optical device system ofclaim 27, wherein the amount of WO₃ is ≧about 2.75 mole %.
 29. Theoptical device system of claim 27, wherein the CTE is ≧about 75×10⁻⁷.30. The optical device system of claim 27 which is a night visiontelescope.
 31. The optical device system of claim 27 which comprisesnight vision goggles.
 32. A fused optical fiber optical device systemcomprising at least one optical component comprising optical fibers andat least one other optical component with which light transmitted insaid optical fibers interacts, wherein said optical fibers comprise acore glass of the following composition in mole %: La₂O₃ 1–23 ZrO₂ 1–10W0₃ ≧2.85 ZnO 1–15 BaO 0–9  B₂0₃ 20–70  CaO 0–7  PbO 5–35 SiO₂ 0–40As₂O₃  0–0.1 Sb₂O₃  0–0.1 Nb₂O₅ 0–3  Al₂0₃ 0–8  Ta₂O₅  0–2.9

and essentially free of CdO and Y₂O₃ with a refractive index n_(d) atleast 1.8 and a CTE of ≧74×10⁻⁷.